By Kari Williamson

NextEra Energy, which owns half of the 4000 wind turbines at the site plans to erect one Siemens wind turbine per 23 of the old wind turbines, some of which are almost 30 years old, over the next four years.

The current wind turbines have capacities in the range of 50-750 kW.

It is hoped that the upgrade of half the wind farm will result in lower bird and bat deaths at the site, which is in a key migratory corridor and a winter spot for raptors.

NextEra Energy will also remove 6.5 miles of overhead electrical lines and about 8 miles of road, according to Mercury News.